| Abstract
| - The development of proton exchange membranes as electrolytes for polymer electrolyte fuel cellsoperating at intermediate temperatures has been achieved combining two approaches: the preparation ofa cross-linked polymer and the formation of covalent organic/inorganic hybrids. A covalently cross-linked sulfonated polyetheretherketone with elevated degree of sulfonation (DS = 0.8) was prepared byreaction with HSO3Cl (SOPEEK). No degradation of PEEK was detected upon sulfonation, but onlycross-linking via sulfonic groups with formation of SO2 moieties was observed. The extent of ramificationwas calculated by analyzing the 1H nuclear magnetic resonance (NMR) spectra of the products and resultedin 20% of the total amount of −SO3H groups present in the polymer. The solubility of the −SO2Clprecursor in organic solvents allowed easy carrying out of functionalization reactions in homogeneousconditions by lithiation and subsequent reaction with SiCl4, thus introducing covalenly linked siliconmoieties (SOSiPEEK) at the ratios 1:0.25 and 1:0.50 per monomeric unit. The products were characterizedby 1H and 13C NMR, attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetricanalysis, and differential scanning calorimetry.
- Sulfonation of PEEK in HSO3Cl leads to a cross-linked polymer where monomeric units are bound via SO2 groups. Post-functionalization with Si(OH)3 groups affords hybrid polymers whose physicochemical characteristics appear to be promising for use as electrolytes in PEMFCs.
|
